The present invention concerns the seismic exploration of the subsoil. Seismic exploration consists of imparting agitation to certain points of the soil which in turn propagates from such points of application, and of collecting at other points measurements of the vibrations propagated to these points, by means of seismic sensors. The analysis of the signals received makes it possible to reconstitute information concerning the layers of the terrain traversed by the seismic waves.
The precision of the information reconstituted in this manner is an inverse function of the speed of wave propagation, because the instants at which the waves arrive at the several points of measurement may be differentiated more accurately.
It is known that seismic waves may be composed of two types of vibration: longitudinal waves vibrating in the direction of the propagation of agitation and transverse waves which vibrate perpendicularly to said direction of propagation (and therefore in a plane tangent to the surface of the wave of the agitation imparted). Of these two types of waves, the second one propagates at a substantially lower velocity.